5 normal forms in relational database theory

1. FIVE NORMAL FORMS IN
RELATIONAL DATABASE THEORY
- AIME

2. TODAY’s CONTENT
 Why we have to learn database normalization
 Bad Relational Database Design – unnormalized
 5 Normalization Forms
 Better Relational Database Design - normailized
 Conclusion

3. Why normalization?
 Database Design
 Minimize Data Redundancy from UPDATE ANOMALIES
 UPDATE ANOMALIES
 Insertion anomalies
 Deletion anomalies
 Modification anomalies

4. Update Anomalies

5. Insert?

6. Insert? DATA
REDUNDANCY!

7. Delete?

8. Delete?
OTHER IMPORTANT
INFORMATIONS
MIGHT BE DELETED

9. Modify?

10. Modify?
MIGHT CAUSE
INCONSISTENCY
PROBLEM

11. BAD DATABASE DESIGN

12. Normalization
Unnormalization
form
1st normalization
form
2nd normalization
form
3rd normalization
form
4th normalization
form
5th normalization
form
Remove
repeating
group
Remove partial
dependencies
Remove
transitive
dependencies
Remove remaining
anomalies from
functional
dependencies
Remove multi-value
dependencies
join
dependencies

13. Unnormalized Form

14. Unnormalized Form to 1st Normalized Form

15. 1st Normalized Form problem
 Data Redundancy
 Might cause inconsistency problem

16. Move to 2nd Normalized Form
Conditions
 It’s already in 1st normalized form
 All attributes have fully functional dependency with primary key, NOT partial dependency
 Get rid of Partial dependencies

17. Move to 2nd Normalized Form
Partial Dependency
 Non-prime field(s) depends on one primary key
 Student_ID + Course_ID Firstname, Surname, Cum.GPA, Position_ID, Position, Scholarship, Course_ID, Course, Credit, Grade, Lecturer_ID, Lecturer
 Student_ID Firstname, Surname, Cum.GPA, Position_ID, Position, Scholarship
 Course_ID  Course, Credit, Grade, Lecturer_ID, Lecturer
 Student_ID + Course_ID Grade
PK PK
PK: Primary Key
FK: Foreign Key
FK FK

18. 2nd Normalized Form
 Separate into relation tables...
PK
PK
Student Relation
Course Relation
FK FK
Student-Course Relation Table

19. Move to 3rd Normalized Form
Conditions
 It’s already in 2nd normalized form
 Get rid of Transitive Dependency
PK
PK
Student Relation
Course Relation
FK FK
Student-Course Relation Table

20. Move to 3rd Normalized Form
Transitive Dependency
 Other attributes, those are not a primary key, cannot define the value of other
attributes
PK
Student Relation
Non-PK

21. 3rd Normalized Form
 Separate into relation tables...
PK
PK
Student Relation
Course Relation
FK FK
Student-Course Relation
FK
PK
Position Relation

22. 3rd Normalized Form
 Separate into relation tables...
PK
Student Relation
FK FK
Student-Course Relation
FK
PK
Position Relation
PK Course Relation FK PK Lecturer Relation

23. Move to 4th Normalized Form
Conditions
 It’s in 3rd normalized form
 Get rid of multi-valued dependencies
PK
PK
Student Relation
Course Relation
FK FK
Student-Course Relation
FK
PK Position Relation
FK PK Lecturer Relation

24. Move to 4th Normalized Form
Conditions
 It’s in 3rd normalized form
 Get rid of multi-valued dependencies
PK
PK
Student Relation
Course Relation
FK FK
Student-Course Relation
FK
PK Position Relation
FK PK Lecturer Relation
Add Research for each lecturer

25. Move to 4th Normalized Form
Multi-valued Dependencies
 AB; Lecturer_IDLecturer
 AC; Lecturer_IDResearch
 But B and C is independent
A B C
PK
PK
Lecturer Relation
Lecturer-Research Relation

26. Final Form – 4th Normalized Form
PK
PK
Student Relation
Course Relation
FK FK
Student-Course Relation
FK
PK Position Relation
FK PK Lecturer Relation PK Lecturer-Research Relation

27. 5th Normalized Form
 Separate more relation and it’s able to join back without spurious tuple occurance
No spurious tuple
PK Position Relation
PK Position Relation

28. Supurios Tuple Example
????
Spurious tuple exist!!

29. PK
PK
Student Relation
Course Relation
FK FK
Student-Course Relation
FK
PK Position Relation
FK PK Lecturer Relation PK Lecturer-Research Relation
OLD
version
NEW version

30. Conclusion
 The purpose of normalization is to
 Reduce data redundacy
 Prevent data inconsistency
 Trade-off
 Performance
 The factors to be considered while normalization
 Single-valued vs Multivalued
 Dependencies
 Partial dependency
 Transitive dependency
 Functional dependency
 Multivalued dependency
 Key and non-Key field relationship